The present invention relates to an apparatus for recording information in an optical information recording medium and/or reproducing information from an optical information recording medium, by using holography, an apparatus for manufacturing an optical information recording medium, and an optical information recording medium.
In the studies of next generation storage technologies, attention has been paid to hologram recording technologies for recording digital information by utilizing holography.
As documents regarding hologram recording, there is JP-A-2004-272268 (corresponding to US2004/0179251). This Publication describes a so-called angle multiplex recording method by which at the same time when a signal light flux is converged upon an optical information recording medium with a lens, reference light as a parallel light flux is applied to generate interference and record a hologram, and multiple recording is performed by displaying different page data on a spatial optical modulator while an incidence angle of the reference angle upon the optical information recording medium is changed. This Publication describes further the techniques of increasing a record density/capacity more than a conventional angle multiplex recording method by converging a signal light with a lens and disposing a numerical aperture (spatial filter) on a beam waist to thereby shorten pitches between adjacent holograms.
Another document is WO2004-102542 (corresponding to US2008/0192311). This Publication describes an example utilizing a shift multiplex method by which light from inner pixels is used as signal light, light from outer pixels in a ring shape is used as reference light, and both the light fluxes are converged upon an optical recording medium with a single lens to record holograms through interference between signal light and reference light near at the focal plane of the lens. 